I think part of the problem is that "marriage" refers to both - a sacred covenant between man and wife made before God, and a secular contract regulated and approved by the secular government where two individuals accept secular commitments in exchange for secular benefit
And some hold THAT'S the problem....
As I understand it, the secular/civil government had NOTHING to do with marriage until the problem of inheritance arose. The Church kept excellent records of marriage and divorce within the diocese but often not nationally, and sometimes there were disputes. SO, the secular/civil state began to keep national records based on licenses and official actions - but still acknowledged that these were religious actions (thus typically REQUIRING a rite, a ceremony, religious or at least religious in appearance - there must be a civil license AND a rite, a ceremony. Weird. Odd.
It kind of makes sense to separate the two. To return marriage and divorce to the church and family. IF a couple wants to be MARRIED, they to to a church or even just to a family group - just as it was for thousands and thousands of years. This for religious and social reasons. They'd be MARRIED in the eyes of the Church (or their families) - but MARRIAGE per se being recognized ONLY by the Church and Family. And divorce also an action of the Church and/or Family. The secular/civil STATE (for legal and economic reasons) can apply "personal corporations" (a legal contract already in existence everywhere) perhaps with certain legal and economic factors. Yes, if a secular government wants to permit such between female volleyball players, it could. But this is not MARRIAGE, it's a CIVIL UNION. It has nothing to do with religion or family, it has to do with the law. They have become a corporation. It's formation and dissolution would be a matter of law. Thus, one MIGHT be married but not be a civil union... and one might be in a civil union but not married.
Would this be a good thing? I'm not sure. But it would eliminate the current confusion of church and state that we now see.
Many years ago, when the UK allowed civil partnerships but not gay marriage, a story made the news. The gist of it was that two elderly sisters, neither of whom had ever married, lived together in the home they shared. Both knew that when one died the other would be rendered homeless because they would have to sell the house to pay inheritance taxes. Had they not been sisters they could have entered into a civil partnership, which would have allowed tax-free inheritance from one to the other. But since they were related that wasn't an option. From a purely secular perspective, given that prohibitions on sexual activity between closely related people appears to be primarily aimed at preventing genetic issues caused by inbreeding, it's hard to see why two sisters shouldn't be allowed to enter into a civil partnership and thereby gain the same benefits as a lesbian couple. Not that it's any of our business but it's probably safe to assume that two elderly sisters won't be doing anything raunchy in the bedroom, and even if they were it's not like there would be any genetic complications caused by unexpected offspring.
In the People's Republic of California, we had the exact same debate some years ago. There was a proposition up for election that would allow "same sex marriage." Those AGAINST this were NOT against civil unions, they were NOT against persons of the same gender having the same legal and economic rights and privileges of marriage, they were against this being MARRIAGE. Those in favor of this make it crystal clear the issu3e for them was NOT equality or rights or privileges, it was entirely about respect, honor, recognition... accepting them as fully MARRIED in every sense. They won.
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